The present invention relates in general to sun protection for the passenger compartment of motor vehicles, and, more specifically, to LCD dimming screens incorporated into the glazings of a motor vehicle.
The shining of direct sunlight into the passenger compartment of a transportation vehicle through any of its window glazings can give rise to the separate problems of glare and heat. The glare reduces the driver's visibility and can be a distraction to the driver and any passengers. Heating of the passenger compartment can result in an increased use of the vehicle air conditioning system which results in increased fuel consumption in an internal combustion vehicle and increased charge depletion for an electric vehicle.
In prior attempts to reduce problems from direct sunlight, tinted glass has been used in the glazings. Tinting is an incomplete solution because it cannot be placed in all areas of the glazings and because the locations of tinting may not correspond to the actual direction of direct sunlight to the driver's eyes at any particular time. Furthermore, tinting reduces visibility when it is dark. On the other hand, with a very bright sun in hot conditions the amount of tinting normally applied may be inadequate to block sufficient sunlight. Furthermore, tinting is not adaptable to current conditions. For example, tinting keeps out sunlight that would provide beneficial heating of the passenger compartment on a cold day. In that instance, the heating that could have been obtained using solar energy for free instead has to be made up for by a heater powered by the vehicle using its energy source (gasoline or battery charge).
Another conventional solution to the heat and glare of direct sunlight has been the use of blocking shades or other mechanical means to selectively deploy over certain window glazings to block to the sunlight. One typical blocking shade is the sun visor usually attached near the top of the windshield for the driver and front seat passenger. Sun visors can be distracting since the driver or passenger must continually physically move the sun visor as the vehicle changes direction. Furthermore, sun visors may be deployed in the same area where an air bag deploys during a crash (e.g., a side curtain airbag), resulting in interference with the air bag deployment. The presence of temporary shades such as a baby shade which attaches by suction cups to a window may also be undesirable during crash events.
Currently known systems let in too much sunlight when and where it is not needed and they otherwise block sunlight when it could be useful. Thus, it would be desirable to better control the blocking or attenuation of direct sunlight in order to reduce the load on climate control systems to compensate for the sunlight to thereby improve fuel economy and to improve driver vision with less glare thereby increasing overall safety.